Given below are four statements with reference to a catalyst. Choose the incorrect statement(s)
(A) A catalyst lowers the potential energy barrier, thus decreasing the activation energy.
(B) A catalyst lowers the Gibbs energy (ΔG) of the reaction.
(C) A small amount of catalyst converts a large amount of reactants into products.
(D) A catalyst can catalyze non-spontaneous reactions also.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (B) and (D) only
(A) A catalyst lowers the potential energy barrier, thus decreasing the activation energy: This is a correct statement. A catalyst provides an alternative reaction pathway with a lower activation energy ($E_a$), allowing more molecules to cross the energy barrier per unit time.
(B) A catalyst lowers the Gibbs energy ($\Delta G$) of the reaction: This is incorrect. A catalyst does not change the equilibrium constant of a reaction, nor does it alter the Gibbs free energy ($\Delta G$) or the enthalpy ($\Delta H$) of the reaction. It only affects the rate at which equilibrium is reached.
(C) A small amount of catalyst converts a large amount of reactants into products: This is a correct statement. Because catalysts are not consumed in the reaction, they are regenerated and can be used repeatedly in many catalytic cycles.
(D) A catalyst can catalyze non-spontaneous reactions also: This is incorrect. A catalyst cannot make a non-spontaneous reaction ($\Delta G > 0$) occur. It can only speed up reactions that are already thermodynamically feasible (spontaneous reactions where $\Delta G < 0$).